I'm too lazy to look for further links at the moment, but there already was a big discussion about this issue
on XDA - blu_spark Kernel Thread...

The fact that the OP5 is back to EXT4 and is not using F2FS should be enough proof that even OnePlus noticed something wrong with F2FS.
It also seems that, once a possible fix for this issue is found, you would probably have to reformat your whole storage with the latest F2FS driver in place, but that's just speculation.

It would be interesting to see how a OP3T with EXT4 and the latest Beta compares to a OP5. All comparisons so far were running stock software, with the old touchpanel driver and old OOS 4.1.6. + F2FS.

Click to expand...

Only solution would be to convert your data partition to ext4. I'm also kinda annoyed by these revelations and have considered going to last build that had ext4 by default if you want to keep bootloader locked. I think Marshmallow for stable and OB14. Install via TWRP get the Oneplus recovery compatible with it, lock bootloader and upgrade to latest via OTA. Seems like too much work though lol

Thanks for the update development team and @Adam Krisko.
Adam can you tell dev team to make that folder in home screen from square to round. it's looking ugly while i am using round icon's on my HOME screen.